Understanding the Nature of Interfaces in Two Dimensional Electronic Devices(UNITE)

缩小计算机基本开关--晶体管--尺寸的能力正受到严重挑战。已经使用了几十年的材料，如硅，预计很快就会达到其性能的极限。这将影响需要降低功率的应用，以及便携式电子产品和手机等高速交换，以及数据存储和服务器中心等更大的电力密集型操作。参与该项目的国际合作研究团队将专注于确定对此类开关使用极限的可行性：原子薄的二维(2D)层。被研究的材料被称为“过渡金属二卤化物”，在原子薄片中生产时是独一无二的，并显示出有望实现高效、低功耗、高性能计算的性能。将研究的一个关键特性是这些材料结合形成晶体管时的表面和界面，以及这些界面的化学和物理属性如何影响和改善晶体管的电开关行为。研究结果可能会降低与推动信息和通信时代的广泛电子设备相关的功耗。这在延长便携式设备的电池寿命方面对社会是有利的，在减少信息和通信技术消耗的总电能方面也对环境有利。该项目名为“了解二维电子设备中接口的性质(UNIT)”，汇集了来自美国、爱尔兰共和国和北爱尔兰的顶尖研究人员，每个研究人员都由各自的政府机构通过美国爱尔兰研发伙伴计划提供资金。该项目将为美国和爱尔兰的五名研究生提供培训，并将包括两所学院之间的学生交流，为通过该项目支持的研究生提供更广泛的科学和文化体验。Unite项目将研究用于低压隧道场效应晶体管的2D过渡金属二卤化物半导体的合成、器件制造和表征。我们将探索通过范德华外延和原子层沉积两种不同的方法来实现大面积合成。同时，将对市场上可获得的块状晶体与技术上相关的触头和绝缘体之间的表面和界面区域进行表征和了解。这将使用原位和非原位表征相结合的方法来完成，包括以下问题：2D半导体表面如何被功能化以允许通过原子层沉积形成均匀且连续的氧化物薄膜；基于电容-电压的测量是否可以应用于2D半导体表面上的金属-氧化物-半导体系统；2D半导体上的金属接触的导电性质是什么；以及原子尺度的电学性质如何与更大面积的接触有关？人们注意到，大面积衬底生长方法的发展不仅展示了将基于2D半导体的晶体管从研究转移到生产的潜力，而且还将为基础研究提供技术上感兴趣的2D半导体材料的来源，这是通过地质来源通常无法获得的。最后，本文的生长和特性研究将应用于基于二维半导体异质结的隧道场效应晶体管的制备。如果Unite团队能够成功地了解与单层或少数层2D半导体中的大面积2D合成、均匀绝缘体沉积、欧姆接触形成和电荷传输相关的问题，这些知识将与一系列潜在的器件架构相关。

The ability to reduce the size of the basic switch in computers, the transistor, is being seriously challenged. Materials that have been used for decades, such as silicon, are anticipated to soon reach the limit of their performance. This will impact applications where reduced power is needed, along with high speed switching, such as portable electronics and cell phones, as well as larger power intensive operations, like data storage and server centers. The collaborative international team of researchers in this program will focus on determining the feasibility of using the ultimate limit for such switches: atomically-thin, two-dimensional (2D) layers. The materials to be studied, called "transition metal dichalcogenides," are unique when produced in atomically thin sheets, and exhibit promising properties that may enable efficient low power, high performance computing. A key property that will be studied is the surface and interfaces of these materials as they are combined to form the transistor, and how the chemical and physical properties of these interfaces impact and improve the transistor electrical switching behavior. The research results could enable the possibility of reducing the power consumption associated with the broad spectrum of electronic devices, which drive the information and communication age. This will be good for society in terms of extended battery life in portable devices and also good for the environment in terms of reducing the total electrical energy consumed by information and communication technologies. The project, entitled "Understanding the Nature of Interfaces in Two-Dimensional Electronic Devices (UNITE)," brings together leading researchers from the USA, the Republic of Ireland and Northern Ireland, each funded by their respective government agencies through the US Ireland R&D Partnership Program. The project will provide training to five graduate students in the USA and Ireland, and will include student exchanges between the Institutes providing a broader scientific and cultural experience for the graduate students supported through the project.The UNITE project will investigate the synthesis, device fabrication and characterization of 2D transition metal dichalcogenides semiconductors for applications in low voltage tunnel field effect transistors. We will explore two separate routes to large area synthesis through van der Waals epitaxy and atomic layer deposition. In parallel, characterization and understanding of the surfaces and interfacial regions between commercially available bulk crystals and technologically relevant contacts and insulators will be conducted. This will be accomplished using a combination of in-situ and ex-situ characterization covering questions such as: how can 2D semiconductor surfaces be functionalized to allow uniform and continuous oxide thin films to be formed by atomic layer deposition; can capacitance-voltage based metrology be applied to metal-oxide-semiconductor systems on 2D semiconductor surfaces; what is the nature of conduction for metal contacts on 2D semiconductors; and how are the atomic scale electrical properties related to larger area contacts' It is noted that the development of growth methods for large area substrates will not only demonstrate the potential to move 2D semiconductor based transistors from research to production, but will also provide a source of technologically interesting 2D semiconductor materials for basic study which are not commonly available through geological sources. Finally, the growth and characterization studies will be applied to the fabrication of a tunnel field effect transistor based on two dimensional semiconductor heterostructures. If the UNITE team can successfully understand the issues relating to large area 2D synthesis, uniform insulator deposition, ohmic contact formation, and charge transport in single or few layer 2D semiconductors, this knowledge will be relevant to a range of potential device architectures.